1. Field
The present disclosure is directed to a method and apparatus for maintaining a battery temperature when temperatures fall below a threshold temperature value. More particularly, the present disclosure is directed to maintaining a battery temperature above a threshold temperature value to allow use of a user device.
2. Introduction
Customers can carry user devices to communicate with other user devices. The scenarios of such use can vary, with one scenario having a customer using a user device in a cold ambient or weather exposure scenario. Such a cold ambient or weather exposure scenario poses significant performance limitations on the ability of the user device to operate.
In particular, if a battery of the user device is allowed to cool down below a certain threshold temperature value, internal chemistry (reaction rate) of the battery becomes sluggish, resulting in low energy delivery and/or high charge transfer impedance. Such battery issues become more pronounced in an older aged battery. For example, a lithium-ion (Li-ion) battery can provide approximately 10-15% power at 0.2 degrees centigrade when new. However, as the Li-ion battery ages, the power that can be produced reduces, depending on a state of health of the Li-ion battery.
An amount of power a battery can produce eventually reduces enough such that the battery cannot generate sufficient power to ‘fire-up’ and run a user device. Such a reduction is particularly a problem when the battery becomes too cold and the user device is being used for an emergency phone call. Such a reduced state can even occur when the battery is in a fully charged state.
Further, charging a battery below a certain threshold temperature value is deleterious to the health of the battery, leading to such problems as Li-plating that causes a drop in battery performance and in extreme cases leads to short-circuits.